This is an exciting and dynamic time for the study of cardiac muscle. The intersections of structural biology, molecular biology and biochemistry hold the promise of rapid advancement in delineating the atomic and molecular details of muscle contraction. Developmental biology, genetics and molecular biology are yielding rapid advancements in the understanding of the program of muscle specification and development. The molecular defects of a number of inherited muscle diseases have recently been delineated and gene therapies are being explored. This training program is based in the School of Medicine of the University of Pennsylvania which provides a unique environment for research and clinical training in the area of cardiac muscle. The basic research aspects of this program draw upon the expertise of the Pennsylvania Muscle Institute, Institute for Human Gene Therapy, and the recently created Training Program in Muscle and Motility. The distribution of trainers in this application includes important representation in the faculty of the School of Medicine in both clinical and basic science departments. This training grant is designed to develop clinician/scientists, clinicians and research scientists who will be leaders in the emerging areas of molecular cardiology, with particular emphasis on cardiac muscle development, function and disease. We are requesting modest support: seven trainees per year. As the range of interests and expertise of the trainers listed on this grant will attest, virtually all of the important areas of current research in cardiac muscle are covered by the trainers listed on this grant. The disciplines utilized by the trainers include molecular biology, genetics, biochemistry, structural biology, cell biology, developmental biology, and physiology. This provides the potential for an unparalleled training environment in the area of cardiac muscle biology.